Moodle 1.4.2 is available from the download page. It contains a variety of fixes and small improvements over previous releases but most importantly it contains fixes for a long list of serious security problems that were discovered recently.
Because of the security implications, I recommend that ALL users of previous versions upgrade to 1.4.2 or later as soon as possible.
Moodle 1.4.3 is planned for early December with more fixes and some performance tweaks.